Planar coil electromagnetic actuators, employed for example to move a shutter blade in a photographic camera, are known. U.S Pat. No. 4,333,722 shows such a planar coil electromagnetic actuator having an armature comprising a planar coil formed for example by photofabrication techniques on a flexible plastic support material. The armature is mounted for movement in a magnetic field by electrically conductive flexure springs that provide a low friction mounting, a built-in restoring force for the actuator, and electrical connections to the planar coils in the armature. An extension of the planar armature forms a shutter blade to cover and uncover an aperture in a camera.
A shortcoming of this arrangement is that the planes of the flexure springs lie perpendicular to the plane of the armature, thereby necessitating a manufacturing step to attach the flexure springs to the planar armature, or where the flexure springs are formed as an integral part of the armature, necessitating an operation to bend the flexure springs out of the plane of the armature into a working position. A further shortcoming of this arrangement is the fact that the flexure springs in their working position are much thicker than the planar armature, thereby placing limits on the overall thickness of the actuator and the allowable locations of the flexure springs.
It is an object of the present invention to provide an electromagnetic actuator of the type having a planar coil armature mounted for movement in a magnetic field by conductive flexure springs that is free from the shortcomings noted above.